Kickout control for bucket loaders



Aug. 4, 1970 A. L. FREEDY KICKOUT CONTROL FOR BUCKET LOADERS 2Sheets-Sheet 1 Filed May 28, 1968 INVENTOR ALLAN L. FREEDY 15v} VW hi-rATTORNEYS B Y 9- a I l Aug. 4, 1970 A. L. FREEDY 3,522,897

KICKOUT CONTROL FOR BUCKET LOADERS Filed May 28, 1968 2 Sheets-Sheet 3RESERVOlR INVENTOR ALLAN L. FREEDY ATTORNEYS US. Cl. 214-764 ClaimsABSTRACT OF THE DISCLOSURE A bucket loader of the type having a bucketpivotally supported on a pair of lift arms, a tilt motor connected tothe bucket by means of tilt linkage and tilt controls operable into adetent position for causing the tilt motors to pivot the bucketforwardly on its lift arms as for dumping. The tilt control is releasedfrom its detent position to terminate forward tilting of the bucket atan appropriate position relative to the lift arms in response to akickout valve mounted on the lift arm and actuated by contact with aportion of the tilt linkage.

Numerous controls are available on bucket loaders for automaticallypositioning the bucket in order to decrease the manipulative duties ofthe operator and to improve operating efiiciency of the machines. Thepresent invention is particularly concerned with a control forterminating forward tilting motion of the bucket in a position suitablefor dumping during its loading cycle. In the prior art, this function iscommonly performed by mechanical stops located on the lift arms andcontacted by the tilt linkage as the bucket approaches its dumpposition. The operator can also perform this function by manuallyshifting the tilt control lever to the hold position. Hydraulic tiltcontrols are indirectly responsive to the engagement of the tilt linkagewith the mechanical stops, by means of a resulting pressure rise in thefluid system, to terminate forward tilting of the bucket. However, asthe size of the bucket loaders in increased, this manner of stopping thebucket causes severe jarring of the loader and the operator and createsundesirable stresses in the tilt and lift linkages for the loader.Repetition of the jarring contact with the stops tends to reduceoperator efficiency as well as being a source of failure for variouscomponents of the loader. Thus, one object of the present invention isto normally terminate forward tilting of the bucket by other than themechanical stops employed in the prior art.

It is another object to provide kickout means to which the tilt controlsare directly responsive to terminate forward tilting of the bucket in aselected position relative to its lift arm means.

It is another object of the invention to normally terminate forwardtilting motion of the bucket just prior to engagement with themechanical stops regardless of the elevation of the bucket on its liftarms.

It is another object to provide means for selectively overriding thekickout control so that the operator can employ the mechanical stopswhen necessary to loosen material from the bucket for example.

The present invention overcomes the problems and fulfills the objectsdiscussed above by providing a kickout which is actuated when the bucketis tilted forwardly to a selected position relative to the lift arms.Forward tilting of the bucket is preferably terminated just prior tocontact of the bucket or its tilt linkage with suitable mechanicalstops. Additional means permits selective overriding of the kickouts sothat the mechanical stops may be employed to loosen material tending tostick to the bucket.

Other objects and advantages of the invention are made United StatesPatent 0 ice apparent in the following description having reference tothe drawings wherein:

FIG. 1 is a side view in elevation of the forward end of a bucket loaderincluding a solid line representation of its bucket in a normal loadingposition and a broken line representation of the bucket in its dumpposition at a selected elevation; and

FIG. 2 is a generally schematic representation, with parts in section,of a hydraulic tilt control system for the loader of FIG. 1.

A bucket loader of the type illustrated in FIG. 1 has a bucket 11pivotally supported upon a pair of lift arms, one of which is indicatedat 12, with hydraulic lift motors, as indicated at 13, for varying theelevation of the bucket by means of the lift arms. A hydraulic tiltmotor 14 is mounted on each lift arm and is interconnected with theloader 10 and bucket 11 by means of tilt linkage 16. The tilt linkageincludes a lever 17 pivotally secured to each lift arm as at 18. Each ofthe levers 17 is pivotally connected at 19 to a rod 21 of one of thetilt motors 14 and at 22 to a link 23 which is also pivotally connectedto the bucket at 24. The bucket is also shown at 11 in a dump positionat a selected elevation with its tilt and lift components also shown bysimilar primed numerals. A mechanical stop 26 is suitably mounted oneach lift arm 12 for engagement by a surface 27 on one of the levers 17with the bucket generally in its dump position indicated at 11'.

The present invention provides a kickout valve, indicated at 28, toterminate forward tilting of the bucket in its dump position and justprior to engagement of the lever 17 with the mechanical stop 26regardless of the elevation of the bucket on its lift arms. The kickoutvalve 28 is suitably positioned upon one of the lift arms 12 foractuating engagement with a cam surface 29 on tilt linkage lever 17 asthe bucket approaches its dump position 11' and just prior to engagementof the lever surface 27 with the mechanical stops 26 (see the brokenline representation of the bucket linkage in FIG. 1). With the kickoutvalve 28 positioned for actuation in this manner, forward tilting of thebucket is always terminated with the bucket in a selected positionrelative to the lift arms so that contact with the mechanical stops 2-6is normally avoided. Provision is made for overriding of the kickoutvalve 28 to permit loosening of material from the bucket by means ofcontact with the mechanical stops as is discussed below with referenceto FIG. 2. It is readily apparent that the same function could beachieved with the kickout valve positioned forwardly on the lift armsfor actuating engagement with the bucket. However, the presentpositioning of the kickout valve tends to reduce the possibility of itsbeing damaged by contact with the ground or debris from the bucket.

The hydraulic control circuit for the tilt motors 14 includes a fluidreservoir 31, a pump 32 and a control valve 33 for selectivelyregulating fluid flow from the pump 32 to one end of the tilt motor 14and communicating the other end of the tilt motor to drain. The controlvalve 33 defines a bore 34 for reciprocably receiving a spool 36. Thecontrol spool 36 is normally urged into a Hold position, indicated at H,by a centering spring 37. The control spool 36 is linked to a pivotallevel 38 which is positioned by a control element 39. Counterclockwiserotation of the lever 38 urges the spool into a Rackback position,indicated at R, so that the control valve 33 communicates pump fluid tothe rod end of the motor 14 while communicating the head end of themotor to drain for causing retraction of the motor. Forward tilting ofthe bucket for dumping results from extension of the tilt motors 14 whenthe lever 38 is rotated clockwise to move the spool to a Dump position,indicated at D. A roller 41 is mounted on a pivotal member 42 which isurged in clockwise rotation by a spring 43 so that the roller 41 comesinto engagement with a cam surface 44 on the lever 38 when the controlvalve spool 36 is moved into its position D. Detenting of the lever 38by means of the roller 41 maintains the control spool 36 in itsrightward position for continued forward tilting of the bucket withoutthe operator being required to maintain the position of the lever 38.

To release the roller 41 from its detent engagement with the lever 38 asthe bucket approaches its dump position (see FIG. 1), a hydraulic slavecylinder 46 has a reciprocable spool 47 coupled to the pivotal member 42and is associated for hydraulic response to the kickout valve 28. Thehydraulic kickout valve 28 has a reciprocable spring loaded spool 48normally extending toward the tilt linkage lever 17. In FIG. 2, the tiltlinkage lever 17 is shown in a position just prior to engagement of itscam surface 29 with a roller 49 mounted on the extended end of the spool48. A conduit 51 communicates the kickout valve 28 with the rod end ofthe tilt motor 14 while another conduit 52 communicates the hydraulickickout valve 28 with the slave cylinder 46. The spool 48 is normallyurged by its spring into a position preventing fluid communicationbetween the conduits 51 and 52. Referring momentarily to FIG. 1, as thebucket is being tilted forwardly and approaches its dump positionindicated at 11', gravity acts upon the bucket tending to causeextension of the hydraulic motors 14. Hydraulic pressure is created inthe rod end of the motors and is communicated to the kickout valve 28through the conduit 51. Engagement of the tilt lever cam surface 29 withthe kickout spool 48 shifts the spool leftwardly and communicates fluidpressure from the conduit 51 to the slave cylinder 46 through theconduit 52. With the lever 38 rotated clockwise for detent engagementwith the roller 41, the pivotal member 42 and the slave spool 47 areshifted leftwardly so that the conduit 52 is in communication with anintemal passage 53 formed in the slave spool 47. A restricted drainpassage 54 in the slave cylinder 46 causes fluid pressure from theconduit 52 to enter the left end of the slave cylinder 46 through thepassage 53 and shift the slave spool 47 rightwardly. This motion of theslave slave spool causes counterclockwise rotation of the pivotal member42 against its spring 43 so that the roller 41 is released from detentengagement with the lever 38. The control valve spool 36 is thenreturned to its Hold position H by the centering spring 37 to terminateforward tilting of the bucket in the dump position shown in phantomlines in FIG. 1. Forward tilting of the bucket is preferably terminatedjust prior to engagement of the tilt lever surface 27 with themechanical stop 26 as is also indicated in the broken linerepresentation of FIG. 1. In this manner, the hydraulic tilt controlsfor the bucket .are directly responsive to the kickout valve 28 tonormally prevent jarring contact with the mechanical stops 26. However,if it is necessary to jar the bucket in order to loosen materialsticking to the bucket surfaces, the operator may cause the tilt linkagelevers to come into contact with the stop 26 by manually maintaining thelever 38 in its Dump position D to override the hydraulic kickout valve28.

What is claimed is:

1. A bucket loader of the type having a bucket pivotally supported on atleast one lift arm for raising and lowering the bucket, comprising tiltlinkage associated with the bucket,

motor means for pivoting the bucket in relation to the lift arm by meansof the tilt linkage,

kickout means associated with the bucket and actuatable when the bucketreaches a predetermined dump position relative to the lift arm, themotor means being directly responsive to actuation of the kickout meansto terminate forward tilting of the bucket, and

a mechanical stop for resisting forward tilting of the bucket justsubsequent to operation of the kickout means, the motor means beingcapable of selective operation to override the kickout means and tiltthe bucket forwardly for effective engagement with the stop.

2. The invention of claim 1 wherein the motor means has detent means formaintaining it in a condition to tlit the bucket forwardly and slavemeans operable to release the motor means from the detent in response toactuation of the kickout means.

3. The invention of claim 2 wherein the kickout means are mounted on thelift arm for actuatable engagement by forward tilting of the bucket.

4. The invention of claim 3 wherein a tilt linkage lever is mechanicallyconnected to the bucket and pivotally supported on the lift arm to enterinto actuating engagement with the kickout means as the bucketapproaches its dump position and prior to engagement of the lever withthe mechanical stop.

5. The invention of claim 2 wherein the kickout means and slave meansare hydraulic cylinders.

References Cited UNITED STATES PATENTS 3,211,310 10/1965 McIndoo 214-7643,402,846 9/1968 Goth 214764 3,429,471 2/1969 Austin et a1. 214764 XHUGO O. SCHULZ, Primary Examiner

